package com.kylin.pc;

import com.sun.corba.se.impl.orbutil.LogKeywords;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 线程之间的通信问题：生产者和消费者问题！等待唤醒，通知唤醒
 * 线程交替执行 A B 操作同一个变量 num = 0
 * A num+1
 * B num-1
 */
public class B {

    public static void main(String[] args) {
        Data2 data = new Data2();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                data.increment();
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                data.decrement();
            }
        }, "B").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                data.increment();
            }
        }, "C").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                data.decrement();
            }
        }, "D").start();
    }
}

//判断等待， 业务，通知
class Data2 {

    private int number = 0;

    Lock lock = new ReentrantLock();
    Condition condition = lock.newCondition();

    //+1
    public void increment() {
        //上锁
        lock.lock();
        try {
            while (number != 0) {
                //等待
                condition.await();
            }
            number++;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            //通知其他线程，我+1完成了
            condition.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            //解锁
            lock.unlock();
        }

    }

    //-1
    public void decrement() {
        //上锁
        lock.lock();


        try {
            while (number == 0) {
                //等待
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            //通知其他线程，我-1完成了
            condition.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            //解锁
            lock.unlock();
        }
    }

}
